Well packer



Feb. 6, 1962 Filed Nov. 19, 1958 B. P. NUTTER WELL PACKER 3 Sheets-Shes?l 1 INVENTOR.

BENJAMIN P. NUTTER HIS ATTORNEY Feb. 6, 1962 B. P. NUTTER 3,019,842

WELL PACKER INVENTOR.

BENJAMIN F? NUTTER wh@ n@ HIS ATTORNEY B. P. NUTTER Feb. 6, 1962 WELL PACKER 5 Sheets-Shes?, 3

Filed NOV. 19. 1958 INVENTOR.

BENJAMIN P. vMUTTER BY/QZZ [x HIS ATTORNEY Testers, Inc., Houston, Tex., a corporation of Terras Filed Nov. 19, 1958, Ser. No. 775,056 Claims. (Cl. 16d- 126) The present invention relates to well packers and, more particularly, to a retrieyable and resettable bridge plug for use in cased boreholes.

In the interests of economy and efficiency, it is advantageous to perform a plurality of completion and remedial borehole operations, such as drill stem testing, squeeze cementing, acidizin'g, luid fracturing, gun perforating and the like, with a minimum of round trips of tubing string into the borehole. In View of the current trend toward drilling to even greater depths, the desirability of multiple purpose tools which reduce rig time by preferably requiring only one-round trip of tubing string to perform an indicated sequence of completion and remedial operations is evident.

This invention is directed to a multiple purpose casing bridge plug especially useful in performing any one of or combination of the above-enumerated operations or operations similar thereto without requiring withdraw-al I nited rates Patent Patented Feb. n 6 1962 ice,

the zone being straddled may be of theoretically unlimitedextent. Y Thesleandother Iobjects of the invention are attained bridge plug .structure including a tubular housing v`housing are friction means for engaging the casing and of the tubing string or the plug to the surface between operations. 1n certain of these operations, such -as squeeze cementing, acidizing and lfluid .fracturing and the like, a bridge plug provides a fluid seal for the casing annulus below the zone to be worked on and must be capable of setting and remaining packed off against differential pressures across the plug acting downwardly thereon. In others of these operations, such as Vdrill stem testing, for example, a bridge plug is used as the lower packer in a straddl'e packer arrangement and at some point the portion of the casing annulus between the packers is reduced to a relatively low pressure. Therefore, the bridge plug must be capable of setting and remaining packed oif against pressure differentials acting upwardly on it.

Frequently it is desired to move to another zone in the well where another sequence of completion and remedial operations is to be performed. It is therefore desirable that a multiple purpose bridge plug be arranged to be quickly and conveniently unseated and reset without withdrawing the tubing string. Such a resetting arrangement, of course, should desirably also .adapt the plug to be unseated yand retrieved to the surface.

It is therefore an object of this invention to provide a new and improved casing bridge plug for use in performing any one of the above-enumerated operations or similar operations or any combination of them with only one trip of the tubing string .into the well.V

Another object of this invention is to provide a new and improved well packer which requires no mechanical linkage to the surface in order to set and remain packed oif against pressure differentials acting in either direction above and below the packer after it is lreleased from its parent tool.

Yet another object of this invention is to provide a new and improved well packer which may be sequenslip` means for., engaging thecasing having integral upper and lowertapered portions, adapted to be pivotally andk slidalzylyl moved outwardly into grippingvengagement with the casing. Longitudinally spaced expander means are carried by themandrel and are-adapted to independently engage and set opposite tapered portionsv of the slip means. The mandrel also carries packer means for 'pack-l ing oif the annulus between the casing and mandrel against pressure diderentials acting upwardly and downwardly thereon. Valve means for'releasably closing the uid passage longitudinally through the mandrel and housing are operative by flow of fluiditherethrough to seal the interior of the plug `against iluid iiow in eitherV direction. The valve means may also be opened to provideaby-pass,passage for uid through the plug when traversingthe well casing.` Locking means may be proyi ed between the housing and mandrel to prevent premature setting of the slips. A retrieving head adapted .,tofwbe operatively connected to a tubing string is releas- `ably connectedto the plug and is adapted to operate the lockingmeans andto-move the valve means to open position.:y

Other and more specific features vof the invention and others of its objects and advantages may be perceived by referring to the following detailed description'. when taken `in conjunction with the accompanying drawings wherein:

FIG. l is a longitudinal sectional' view of a bridge plug constructed in accordance withtiieipresent invention and shown in its running in position releasably lconnected tothe retrieving head;

FIG. 2 is a cross-section of the yapparatus of FIG. l

taken on the line 2--2 thereof looking in the :direction of the arrows;

FIGS. 3a to 3g are simplified schematic representations of an 'elevation View of the apparatus of the present invention showing in particular the slots in the retrieving head and housing and the positions of the mandrel pins in these slots for the various manipulations required to operate the apparatus and for'th'e various positions the apparatus takes;

FIG. '4 is an elevational view partly in section and partly in vdiagram form of a portion of the apparatus of FIG. l shown in the position it takes when packing ott against pressure differentials across the apparatus acting upwardly thereon, the retrieving Aihead having 'been removed;

FIG. 5 is an elevational View partly in .section land partly kin diagram form of a portion of the apparatus of FIG. 1 shown in the position it takes when packing oit :against pressure diferentials across the apparatus acting downwardly thereon; and

FIG. 6 is an elevational view partly in section and partly in diagram form -of a portionof the apparatus of FIG. 1 shown in the going out position, the retrieving head having been reconnected.

In FIG. '1 is shown a well packer 10 constructed in accordance with the principles of the present invention and extending through a well casing 11 which traverses earth formations. The well packer is specifically designed to vfunction as a casing bridge plug and hereafter will be referred to as the bridge plug 10. The bridge plug 10 comprises a housing 15 at its lower end within which is concentrically and 'slidably received for limited longitudinal 'movement relative thereto the lower end of a tubular mandrel 16. A retrieving head 17 is releasably secured to the upper end of the mandrel 16 and is adapted to be operatively connected to a tubing string (not shown) for movement therewith.

The housing 15 includes an upper tubular section 20 and a lower tubular section 21 threadedly secured together. The exterior of the section 2l is formed with a plurality of at mounting surfaces 25 to each of which is fastened a friction pad assembly 27 providing friction means for engaging the casing. Although but two are shown in this view, four such equally spaced mounting surfaces 25 and friction pad assemblies 27 are provided in the preferred embodiment illustrated. Each friction pad assembly 27 conventionally includes a mounting plate 3l), a flanged retainer frame member 31 iixed thereto and a wall engaging pad 32 received within the frame member 31 and spring urged outwardly against the casing.

A plurality of slips 35 are pivotally and slidably carried by the upper portion of housing section 20 for pivotal radial movement outwardly into gripping engagement with the casing. The slips 35 are generally rectangular members each having upper and lower portions rigidly connected together at their wide ends. The outer faces of the upper and lower portions are sections of opposite slightly sloping frusto-conical surfaces. In the embodiment illustrated the slope of these surfaces is about 2, but if desired this slope may be somewhat less, i.e. substantially or somewhat greater. The outer face of the upper portion of each of the slips is provided with downwardly pitched serrations or wickers 36 and the outer face of the lower portion is provided with upwardly pitched serrations 37. Each of the slips 35 is loosely slidably received within a rectangular opening 4@ in the housing section 20 (see FIG. 5) one is positively secured to the section 20 by a horizontal pin 42 located midway relative to the length of the opening 4l). Each pin is spaced radially from the longitudinal axis of housing and is received within a radially extending slot 43 in its corresponding one of the slips 35, as best seen in FIG. 2.

Formed on the inner surface of each of the slips 35 are upper and lower sloped at wedging surfaces 45 and 46, respectively. The upper surface 45 is sloped upwardly and outwardly, while the lower surface 46 is sloped downwardly and outwardly. These wedging surfaces are adapted to be independently engaged by appropriate expander means on the mandrel 16 in such a manner as to slide each slip 35 radially outward along its slot 43 while initially simultaneously pivoting it approximately 2 about its pin 42 to bring the wickers 36 or 37 into parallelism with the casing. Thus, the downwardly tapering upper wickers 36 grip the casing when the plug sets against pressure differentials acting downwardly on the plug while the upwardly tapered lower wickers 37 grip the casing when the plug sets against pressure differentials acting upwardly from below the plug. Premature outward movement of the slips 35 such as in response to gravity, for instance, is prevented by upper and lower leaf springs 48 for each of the slips. The leaf springs 48 are fastened to the housing section and engage upper and lower terminal portions of the slips 35 to bias them to an inwardly retracted position.

The mandrel 16 is an elongated tubular member carrying external vupper and lower slip expander means 50 and 51. It further has external, oppositely-directed packer cup assemblies 53 and 54 positioned above expander 50. In addition, valve means 56 is provided for selectively blocking the uid passage through the mandrel.

More specifically, the lower expander means 51 is provided by a plurality of upwardly and inwardly sloping flat surfaces 60 adapted to slidably engage the slips 35 to apply an outwardly directed setting force thereto when the bridge plug sets against a differential pressure acting upwardly on the plug. For ease of manufacture and assembly, the surfaces 60 are included on a lower mandrel sub 61 which is threadedly secured to a tubular section 62 connecting theupper and lower expander means. The lower annular portion 63 of the sub 61V slidably contacts the housing section 20 to assist in assuring that the wedging surfaces 60 apply substantially equal radial forces to each of the slips 35. The upper expander means 50 is carried by the mandrel 16 at a xed longitudinal distance from the lower expander means 51 and includes downwardly and inwardly sloping wedgng surfaces 66 adapted toslidably engage the upper slip wedging surfaces 45 to apply an outwardly directed setting force thereto when the bridge plug sets against pressure differentials acting downwardly on the plug.

The motion of the mandrel 16 relative to the housing 15 is limited and guided by a pin and slot arrangement. A pairvof diametrically opposite generally H-shaped index slots 7G and 71 are cut into the housing section 20 below the slips 35. Received within each index slot is one of a pair of diametrically opposite setting pins 72 and 73 xed to and projecting laterally from the lower end of the mandrel 16.

The shape of the index slots is better perceived from any one of FIGS. 3a through 3g, which are simplified diagrammatic views illustrating the manipulations required to operate the bridge plug. Represented in these figures are the mandrel 16 received within the housing 15. The housing is provided with the friction means 27 yand the guiding and locking slot 71. Also shown is the retrieving head 17 releasably secured to the upper end of the mandrel 16 by Ia pin and J-slot arrangement to be described hereafter, and the upper and lower packing cup assemblies 53 and 54.

The H-shaped slot 71 comprises a long leg 80 and a short leg 81 circumferentially spaced from leg 80 along housing 15 centered longitudinally relative to leg 80. A centrally located connecting portion 82 extends between legs 80 and 81. The slot 70 is identical to slot 71 and has a similar circumferential orientation relative to housing 15 whereby the two setting pins 72 and 73 are alt every position in corresponding portions of the two s ots.

The dimensions and arrangement of the short leg 81 are chosen such that the expander means 50 and 51 are prevented from moving into setting position when the pin 73 is within this portion of the slot 71. The long leg 80, however, is of suiiicient length to permit the expander means to move upwardly or downwardly, as the case may be, into full setting engagement with the slips 35. When running in and going out, the pins 72 and 73 are located within the short legs of their respective slots, and since rotation is required to move into the long legs, it follows that this pin and slot means locks the bridge plug 10 against premature setting.

As mentioned earlier, the mandrel 16 carries packer means for packing ol the annulus between the mandrel Y 16 and the casing 11 against pressure differentials in either direction acting upwardly or downwardly thereon. This packer means is located above the expander means 50 and comprises the upper and lower packing cup assemblies 53 and 54 which are structurally identical, but oppositely directed. As shown in FIG. l, the lower packing cup assembly 54 includes a flanged shoe member 9t, a ring-like spider 91 therebelow in contact with the mandrel, and a packer cup 92 of an elastomer material secured between these elements. The free end of the cup 92 is inherently biased outwardly into engagement with the casing 11 and is spaced from the mandrel 16 whereby Well fluid moving upwardly in the casing annulus in response to higher pressures below the plug 10 spreads the cup 92 into sealing engagement with the casing.

The expander means 50 is carried by a mandrel sub 95 threadedly connected at its upper end to a valve sub 96 having a longitudinal bore 97 and in turn, threaded to a upper sub 98. In order to secure the lower packing cup assembly 53 to portion 96 of the m'andrel 1.6 in a manner resisting the high shear pressures involved, the assembly 54 is received between opposing shoulders 100 and 101 on the subs 95and 96, respectively, which are tightened toward each other to the desired degree. In similar fashion, the upper packing cup assembly 53 including the upper cup 104 is wedged between opposing- 5 when being lowered in the casing, the packing cup assemblies 53 and 54 trictionally engage the casing and the retrieving head 17 exerts a downward force on the pin 130 urging 'it to the bottom of the mandrel slots. When being raised withinthecasing, the head 17 exerts an upward forceA on the retrieving pin 130 urging it to the y top vof the mandrell slots. As will subsequently be more shoulders on the subs 96 and 98. It is evident that iluid Y at a location between the packer cup assemblies 53 andk 54. Additional equalizing ports 105 are located in sub 97 in the vicinity of cup 104, while equalizing ports 169 are provided in sub 95 adjacent cup 92.

The valve means 56 provides means for blocking the fluid passage through the bore of mandrel 16 against the flow of fluid therethrough in either direction and is also arranged to allow the ilow of fluid therethrough in either direction, as is desired when lowering or raising the plug' within the casing 11. Specilically, valve means 56 includes a chamfered upper valve head 114 which is movable into and out of engagement with an upper valve seat 115 provided by the chamfered upwardly facing end 116 of sub 96. Valve 114 is actuated to a position closing the bore of mandrel 16 in response to the downward flow of uid resulting when there is a higher pressure of fluid above the plug 1t) than below. To block the bore oi' mandrel 16 against the upward flow of lluid resulting from higher pressures below the plug 1t) than above, a lower valve is provided by a valve ball 120 which is movable into and out of engagement with a lower valve seat 121 provided by the charnfered downwardly facing end 122 of sub 96.

Control and connecting means are provided between the upper and lower valves whereby only one valve may be closed at any one time and whereby both valves may move to open position to provide a iiuid by-pass when raising and lowering the plug within the casing. To this end, the upper valve head 114 is xed to a stem 125 extending longitudinally through the bore 99 of sub 96 and whose headed upper end 126 is slidable within a cylindrical lost motion housing 127. The cylinder 127 is secured by a connector rod 128 to a laterally extending retrieving pin 130 which has limited longitudinal movement within diametrically opposed slots 135 and 136 in the mandrel sub 9S. The outer ends of the pin 130 are headed in order to align the stem 125 in bore 97 to assure proper seating of valve head 114 with the upper valve seat 115. At the upper end of sub 95, a pin 138 extends diametrically across at a location below the valve ball 120. Thus, pin 138 prevents the valve ball 120 from blocking the bore of the mandrel 16 when the bridge plug is being retrieved.

When being lowered or raised within the casing 11, the bridge plug 1G is releasably connected at its uppermost end to another well tool or directly to the tubing string by means of the retrieving head 17. The retrieving head 17 includes a tubular housing 141 having an open lower end to enable/it to slidably tit over the upper end of the mandrel 16 above the upper packing cup 104. A pair of diametrically opposing J-slots 142 and 143 are formed in the housing 141 to receive opposite ends of the retrieving pin 135. As can be better seen in FIG. 3a, the slot 143 includes a short, vertical leg 145 and a diagonal leg 146 having a large downwardly opening entrance 146 extending to the lower end of the housing 141.

The retrieving pin 130 is received within the J-slots 142 and 143 when running in and going out or when moving to another depth within the casing 11 and is accordingly urged toward one end or the other of their respective mandrel slots 135 and 136 (FIG. 1). Thus,

clear, the retrieving head cooperates with the upper valve 114 when the plug is being lowered through the casing to prevent it from seating. When the plug is raised through the casing, the retrieving head actuates the stem 125 to engage the lower valve ball to prevent it from seating.

ln a typical operation employing the bridge plug 10, the retrieving head 17 is operatively connected to a tubing string and opposite ends of the retrieving pin 130 are received within the J-slots 142 and 143. Ordinarilythe bridge plug 111 is used in conjunction with a packer and the retrieving head is connected below the packer. For instance, the bridge plug may be used with the full opening packer by the same inventor which is described in application Serial No. 774,910, tiled November 19, 1958, and assigned to the same assignee as the present invention, in which case the retrieving head 17 is secured to the lower end of the packer mandrel. However, the bridge plug 10 may, if desired, be used as an independent unit without an upper packer or other parent tool in the tubing string.

When being lowered through the casing 11, the bridge plug 10 is in the operating condition shown in FIG.r 1. The upward ow of fluid through the housing and mandrel lifts the lower valve ball 120 toward the lower valve seat 121. However, the retrieving head 17 exerts a downward force on the retrieving pin 130 maintaining it at the bottom of the mandrel slots 135 and 136. Thus, the stem extends below the lower valve seat 121 even though the lost motion connection 126, 127 is fully retracted due to upward force exerted on the bottom of the valve head 114 as a result of iluid ilow through the bore of mandrel 16. Since the stem 125 is positioned to prevent the lower valve ball 120 from seating, a fluid passage through the plug is maintained.

It can be seen from FIG. 3a that when running in, the setting pin 73 and also pin '72 are received within the short legs 81 of the respective housing index slots 71 and 70, whereby the bridge plug is locked against premature setting. Since the friction means 27 frictionally engages the casing during the descent and retards motion of the housing 15, the setting pins ordinarily remain at the bottom of the short legs 81, but in any event motion of the mandrel 16 relative to the housing 15 is restricted to the path of the short leg 81 which is so arranged as to prevent the expander means 50 and 51 from being brought into setting engagement with the slips 35.

On reaching the depth in the casing where it is desired to set the' bridge plug, a series of operations are performed first to unlock the bridge plug and then to release the retrieving head 17 from the mandrel 16. The unlocking operation requires moving the setting pins 72 and 73 to the long legs 30 of the index slots 76 and 71, wherein suicient longitudinal movement of the mandrel relative to the housing enables the expander means 561 and 51 to move into setting engagement with the slips 35. Hereafter the description will proceed with respect to only one set of pins and slots as illustrated in FIGS. 3a to 3g,

' it being understood that the diametrically opposite sets of pins and slots have identical relative positions. The arrows in these figures represent the rotation and longitudinal movement given to the tubing string at the surface to move from the position illustrated in one ligure to that of the next ligure.

To accomplish the unlocking, the tubing string is first lowered to assure that the pin 73 is at the bottom of leg 81 and that the pin is at the top of the curved portion of the J-slot 143, as shown in FIG. 3oz.v Motion of the housing 15 is retarded relative to mandrel 16 and retrieving head 17 due to the engagement of the friction means 27 with the casing. The engagement of the packing kcup assemblies 53 and 54 with the casing also retards motion of the mandrel 16 to some extent. The tubing is then turned to the left about two revolutions and subsequently lifted. These manipulations position the setting pin 73 at the top of the short leg 81 and the retrieving pin 130 at the bottom of the short leg 1115 of the J-slot 143 as seen in FIG. 3b. To position the setting pin in the long leg 8l) of index slot 71, the tubing next is simultaneously lowered and rotated to the right about two revolutions. This combination of forces moves the setting pin to near the lower end of the long leg Sti of the index slot 71 and positions the retrieving pin 131i at the top of the short leg of the J-slot 142, as in FIG. 3c. This movement may partially set the slips 35 but does not move them into strong gripping engagement with the casing.

To release the retrieving head 17 from the mandrel 16, the tubing is simultaneously rotated to the right about two revolutions and lifted. This movement slides the curved portion of diagonal leg `1456 along the pin 130 and allows the housing 141 to slide completely olf the upper end of mandrel 16.

At this time there is no mechanical connection between the retrieving head 17 and the mandrel 16 and housing 15, these latter assemblies being maintained in place by the frictional engagement with the casing of the friction means 27 and the packing cup assemblies 53 and 54. Full setting of the slips 35 into gripping engagement with the casing has not yet taken place. At this point in a cycle of operation the slips 35 may be set in response to pressure differentials in either direction above or below the plug 10 inasmuch as setting does not require mechanical linkage to the surface.

Let it be assumed, for example, that a Zone above the plug is to be tested for fluid production. In other words, the plug 10 is to be set against higher pressures below than above it which creates an upward lifting force. For this condition, the lower expander means S1 should move upwardly relative to the housing to engage the lower slip wedging surface 46 and exert an outward force thereon. The upward force to bring about this movement is supplied when the pressure above the plug is reduced. As a consequence of the resulting pressure differential fluid flows upwardly through and against the plug.

As can be seen in FIG. 4, Valve ball 120 and upper valve head 114 are lifted by this upward flow of fluid, and

they carry the stem 125 and retrieving pin 130 upwardly. In the absence of retrieving head 17, the retrieving pin 130 slides upwardly in mandrel slots 135 and 136, thereby permitting the stem 125 to rise a distance sufficient to enable the valve ball 120 to seat on the lower valve seat 121.

After the valve ball 120 seats, there is no fluid passage either through the plug or around the plug, the casing annulus being now substantially fluid tight because of the engagement of the lower packing cup 92 with the casing wall. As the differential pressure across the plug is built up, the upwardly acting force created thereby increases until this lifting force lifts the mandrel 16 relative to the housing 15 in the direction of the long vertical leg 80 of the index slot 71 (see FIG. 3d). Movement of the housing 15 is inhibited because of the frictional engagement of the casing by the friction pad assemblies 27. The lower mandrel surfaces 6) are consequently carried upward into sliding engagement with the lower wedging surfaces 46, exerting an outwardly directed setting force thereon which simultaneously urges the lower portion of the slips 35 radially outward against the force of the leaf springs 48 and pivots the lower portion of the slips 35 about 2 into parallelism with the casing. At this point in the cycle of operation, the wedging surfaces 46, 60 are parallel and further upward movement of mandrel surface 6l) results solely in a radially outward movement of the lower portion of the slips 35 until the outer surface thereof bearing the downwardly pitched serrations 37 grippingly engages the casing. This gripping contact produces a resisting force which prevents the bridge plug from moving upward in the casing due to any lifting force created by the upwardly acting differential pressure. r[he rresisting force increases, as does the outwardly directed sealing force on the lower packing cup 92.y

Before describing the manner in which the plug 1@ is unseated, operation in the case of higher pressure above Vthe plug than below it will be considered such as is the case when acidizingfluid fracturing, squeeze cementing or the like. After the tool is lowered in the casing in the condition illustrated in FIG. l, fluid pressure above the plug is increased to provide downwardly acting differential pressure. This produces a downward flow of well fluid through the plug which acts on the valve head 114 to urge it into seating engagement with the upper valve seat as shown in FG. 5. The retrieving pin 13G, being free of the retrieving head 17, of course, slides downwardly within the slots 135 and 136, and the lower valve ball 121B drops and restson the pin 13S.

With the valve means 56 closed there is no fluid communication either through the plug or around-the plug, the casing annulus being sealed by the engagement of the upper packing cup 104 with the casing. As the differential pressure across the plug builds up, the mandrel 16 is forced downwardly within the housing 15 in the direction of the long leg 89 of the index slot 71 (see FIG. 3e), while friction pad assemblies 27 hold the housing essentially xed with respect to the casing. The mandrel wedging surfaces 66 slide farther down along the slips wedging surfaces 45 and the upper downwardly sloping wickers 36 are brought into parallel gripping engagement with the casing wall in a manner similar to that described above, i.e., the upper half of the slips 35 is initially rotated about 2 and moved radially outward. Thereafter, further engagement of the wedging surfaces produces only radially outward movement until the slips are set. As heretofore explained, the initial movements of this setting action may take place when the plug is unlocked and the retrieving head 17 is released from the mandrel 16. This gripping engagement produces a resisting force proportional to the dilerential pressure and prevents the plug from being forced downwardly in the casing by treating or squeezing pressures or the like applied above the plug. The outward sealing force of the upper packing cup 104 also increases as the pressure above it increases.

Since the setting of the slips takes place without any mechanical linkage to the surface and since the valve means 56 is arranged to seat from either longitudinal direction in response to flow of fluid through the plug, it follows that any sequence of setting successively against differential pressures acting in either direction may be accomplished. Thus, after being released from the retrieving head 17, the bridge plug 10 may set in either direction either against differential pressures acting downwardly or upwardly. Thereafter, the mandrel 16 moves to the opposite setting position in response to the changing differential pressures and does so automatically for any desired pressure sequence.

To unseat the bridge plug 10 and bring it to the surface, or for resetting it at another depth in the casing, the retrieving head 17 may be reengaged with the mandrel 16 and the setting pin 73 must be repositioned in the locking portion 81 of the index slot 71. In this way, longitudinal travel of the lower expander means 51 is limited to prevent it fom setting the slips 35.

Referring to FIGS. 3f and 3g, the tubing is first lowered until the retrieving pin enters the downwardly opening wide-mouthed portion of the J-slot 143 and rides upwardly in the diagonal leg 146 to the top thereof. After contact with the upper edge of the curved portion of the J-slot is made, weight is applied downwardly on the tubing to position the setting pin 73 at the lower end of the long leg Sli of the index slot. Of course, if the plug had previously been in the position shown in FIG. packing olf against a pressure differential acting downwardly, the pin 73 is already at the bottom of leg et?. But if the plug has been in the FlG. 4 position, packing oif against a pressure differential acting upwardly,A the application of weight to the tubing at this point slides the pin 73 downwardly in the slot Sti. To move the pin 73 to the top of the short leg 81 of index slot 71 and to move the pin 1.30 to the bottom of the short leg 14S of the J-slot 145, the tubing is rotated to the left until a small amount of resistive torque is noted and then is lifted. Y

The bridge plug is now ready to be retrieved.

During retrieving, the valve means HS6 assumes the operating condition shown in FIG. 6. The upward force exerted by head 17 on the retrieving pin 13? causes it to move to the upper ends of Ytheimandrel slots 135 and 136, keeping the upper valve head 114 off its seat 115 even though the downward ow of fluid through 'the plug exerts a downward force thereon causing the lost motion connection 126, 127 to become fully extended. The lower valve ball 129 drops and rests against pin 138. There is consequently a fluid by-pass through the plug as it is withdrawn through the well to the surface or to a lesser depth where it is desired to reset the plug as already explained.

Should it be desired to unseat the bridge plug 10 and reset at a lower depth, the same unseating procedure as set forth above is carried out, that is, the setting pin '73 is moved to the upper end of the short leg S1 of the index slot and the retrieving pin 13@ is positioned at the closed end of the J-slot 143. Thereafter, however, the tubing string is lowered, and the pins and slots move to their FG. 3a positions while the valve means 56 assumes the operating condition of FIG. l. At the new lower level the plug may be reset as explained with regard to FGS. 1, 4 and 5.

The bridge plug 1li thus may advantageously be unseated and retrieved to the surface or may be reset at a new higher or lower level. A wide variety of operations may be carried out with the plug constructed in accordance with this invention since it sets against diiferentialpressures acting upwardly or downwardly thereon without mechanical linkage to the surface or a parent tool. Haw ing set against differential pressures acting in one direction, it is capable of automatically setting against differential pressures acting in the other direction, the setting force being provided by the liow of fluid through the tool and by the diiferential pressure itself. Only one trip of the tubing string is necessary to initially lower the plug into the well and to retrieve it to the surface at the cornpletion of the final operation.

The plug 10 is especially suitable for use below a full opening packer as the lower packer in a straddle packer arrangement. The distance that may be straddled is virtually unlimited due to the fact that the bridge plug is released from the retrieving head after it is unlocked. After being released, it will set and pack off against pressure differentials in either direction. With the plug set below the casing perforations and the full opening packer set above them, such operations as drill stem testing, acidizing, fluid fracturing, squeeze cernenting and gun perforating may be carried out. When testing is to be l trieved and removed from the well or it may be relocated with the full opening packer at a dierent location in the Wen;

l It is to be understood that the invention has been described and illustrated with regard to apreferred embodiment only, and that various changes and modifications may be made and equivalents utiliized by those skilled in the art without exercising invention or departing from the spirit thereof as set forth in the following claims.

What is claimed is:

1. In a bridge plug positionable within a casing: a tubular housing, friction means carried by said housing for engaging the casing, slip means pivotally and slidably carried by said housing for pivoting and radial movement outwardly into gripping engagement with said casing, a tubular mandrel having a lower end slidably received within said housing for limited longitudinal movement relative thereto, longitudinally spaced expander means carried by said mandrel for independently wedging al-w ternate opposite ends of said slip means into gripping engagement with the casing, elastomer packing means car ried by said mandrel above said expander means for packing olf against pressure differentials acting upwardly and downwardly thereon, valve means received in said mandrel operative by ow of fluid through said tubular mandrel and housing for blocking the flow of fluid therethrough in either longitudinal direction, and a retrieving head adapted to be operatively connected to a tubing string releasably connected to said mandrel and to portions of said valve means and urging said valve means to open positions permitting liow of fluid through said man-` drel and housing in either direction.

2. n a retrievable bridge plug positionable within a casing, a tubular housing, friction means c'ar'r'ied by said housing for engaging the casing, bridge plug slips each having oppositely tapering upper and lower portions rigidly connected together and bearing casing gripping serrations on the outer faces thereof, means mounting said slips on said housing' for radial and pivotal movement outwardly into gripping engagement with the casing, a tubular mandrel having a lower end slidably received within said housing for limited longitudinal movement relative thereto, upper and lower expander means spaced from one another at a fixed distance and carried by said mandrel for independently wedging alternate opposite ends of said slips into gripping engagement with the casing, packer means carried by said mandrel above said expander means for packing off against higher pressures thereabove and therebelow, releasable valve means received in said mandrel operative by pressure differentials for blocking the longitudinal flow of liuid through said tubular mandrel downwardly and upwardly, and a retrieving head releasably connected to said mandrel, said retrieving head being arranged to cooperate with said valve means to' hold said valve means in positions permitting now of uid through said tubular mandrel and housing in either direction.

3. In a bridge plug positionable within a casing, a tubular housing, friction means' carried by said housing for engaging the casing, bridge plug slips each having opposite'ly tapered upper and lower portions rigidly connected at their wide ends and bearing casing gripping serrations on the outer arcuate faces thereof, pin and slot means mounting said slips on said housing for pivotal and radial movement: outwardly into engagement with the' casing, a tubular' rha'ndr'el having a lower end slidably received within said housing',- longitudinally spaced expander means carried by said mandrel and arrar'ig'ed to independently engage alternate opposite ends of said slips to set said slips and limit longitudinal movement of said mandrell within said housing, upwardly and downwardly directed packer cup means carried by said mandrel above said expander' mealisifor' engaging the casing and packing off against pressure differentials in either direction above and below the plug", valve meansmounted in said mandrel for movement between positions blocking upward ow of fluid through said mandrel and blocking downward flow of uid through said mandrel, and a retrieving head adapted to be operatively connected to a tubing string releasably connected to said mandrel and cooperaing with said valve means to move said valve means to positions allowing tlow of fluid through said mandrel in either direction.

4. In a retrievable and resettable bridge plug positionable within a casing, a tubular housing, friction means carried by said housing for engaging the casing, bridge plug slips each having oppositely sloped upper and lower portions rigidly connected together and bearing casing gripping serrations, means pivotally and slidably mounting said slips on said housing for pivotal and radial movement outwardly into gripping engagement with the casing, a tubular mandrel having a tiuid passage longitudinally therethrough slidably received within said housing, longitudinally spaced upper and lower expander means secured to said mandrel and arranged to independently engage alternate opposite inner ends of said slips to move said slips into gripping engagement with the casing, pin and slot means for limiting motion of said mandrel relative to said housing to releasably prevent said expander means from setting said slips, packing means carried by said mandrel `for engaging the casing and packing o against pressure differentials acting upwardly and downwardly thereon, valve means received in said mandrel operative by ow of uid in either direction through said tubular mandrel for releasably blocking said uid passage, and a retrieving head adapted to be connected to a tubing string releasably connected to said mandrel and "alve means and urging said valve means to positions unblocking said fluid passage.

5. In a retrievable and resettable bridge plug positionable within a casing, a tubular housing, friction means carried by said housing for engaging the casing, bridge plug slips having upper and lower oppositely tapered portions rigidly connected together at their wide ends, means pivotally and slidably mounting said slips on said housing for pivotal and radial movement outwardly into gripping engagement with the casing, means urging said slips inwardly to an initially retracted position, a tubular mandrel having a lower end slidably received in said housing for limited longitudinal movement relative thereto said mandrel having a fluid passage longitudinally therethrough, an upper expander means carried by said mandrel for movement downwardly therewith into setting engagement with the upper portion of said slips, lower expander means carried by said mandrel for movement upwardly therewith into setting engagement with the lower portion of said slips, upper and lower packing cups carried by said mandrel above said expander means for packing ol against differential pressures acting downwardly and upwardly thereon, valve means received in said mandrel operative by ow of uid longitudinally through said tubular mandrel in either direction for blocking said uid passage, and a retrieving head adapted to be operatively connected to a' tubing string releasably connected to said mandrel and to said valve means for holding said valve means in positions unblocking said uid passage for uid flow in either direction.

6. In a retrievable and resettable bridge plug positionable within a casing, tubular housing, friction means carried by said housing for engaging the casing, bridge plug slips having oppositely sloped upper and lower face portions rigidly connected together and bearing casing gripping wickers, means pivotally and slidably mounting said slips on said housing for pivotal and radial movement outwardly into gripping engagement with the casing, a tubular mandrel having a lower end slidably received within said housing for limited longitudinal movement relative thereto, upper expander means xed to said mandrel for downward movement therewith into setting engagement with the upper portion of said slips, lower expander means xed to said mandrel for upward movement therewith into setting engagement with the lower portion of said slips, pin and slot means for releasably limiting longitudinal movement of said mandrel relative to said housing to prevent premature setting engagement of said expander means with said slips, upper and lower packing cups secured to said mandrel above said expander means for packing olf against pressure differentials acting upwardly and downwardly thereon, an upper valve within said tubular mandrel for blocking iluid iiow therethrough and movable to a closed position by pressure differentials acting downwardly thereon, a lower valve within said tubular mandrel for blocking iiuid How therethrough and movable to a closed position by pressure diderentials acting upwardly thereon, a retrieving head adapted to be operatively connected to a tubing string, and means for releasably connecting said retrieving head to said mandrel, said means including portions cooperating with said upper and lower valves to urge said valves to open positions allowing uid flow through said tubular mandrel in `either direction.

7. ln a retrievable and resettable bridge plug, positionable within a casing, a tubular housing, friction means `for engaging the casing carried by said housing, bridge plug slips each having oppositely tapered upper and lower portions rigidly connected together at their wide ends and bearing casing gripping wickers on the outer arcuate faces thereof, pin and slot means mounting said slips on said housing for pivoting and sliding movement outwardly into gripping engagement with the casing, a tubular mandrel received within said housing for limited longitudinal sliding movement relative thereto, said tubular mandrel and housing defining a longitudinally extending uid passage therethrough, oppositely directed packing cup assemblies carried by said mandrel for packing olf against said casing in response to pressure differentials acting upwardly and downwardly thereon, a retrieving head adapted to be operatively connected to a tubing string for movement therewith, valve means within said tubular mandrel, said retrieving head being releasably connected to said valve means to urge said valve means to open positions unblocking said uid passage, said valve means being arranged when released from said retrieving head to move to closed positions blocking said uid passage in response to upward and downward flow of fluid therethrough, upper expander means carried by said mandrel for movement downwardly therewith into sliding engagement with the upper portion of said slips to urge said upper slip portion wickers into gripping engagement with the casing, and lower expander means carried by said mandrel for movement upwardly therewith into sliding engagement with the lower portions of said slips to urge said lower slip portion wickers into gripping engagement with the casing.

8. In a well packer positionable within a casing, a tubular housing, friction means carried by said housing for engaging the casing, bridge plug slips having oppositely tapered upper and lower portions rigidly connected together at their Wide ends, casing gripping wickers on the outer faces of said upper and lower portions, means pivotally and slidably mounting said slips on said housing for pivoting radial movement outwardly into gripping engagement with the casing, 'a tubular mandrel slidably received within said housing for limited longitudinal movement relative thereto, said tubular mandrel and housing defining a longitudinally extending iiuid passage therethrough, upwardly and downwardly directed packing cup assemblies carried by said mandrel for packing oft against said casing in response to pressure dilerentials acting upwardly and downwardly thereon, a retrieving head adapted to be operatively connected to a tubing string for movement therewith, valve means Within saidl tubular mandrel, said retrieving head being releasably connected to said valve means to hold said valve means in positions allowing uid flow through said tlud passage in either direction, said valve means being ar ranged when said retrieving head is released therefrom to move to positions blocking said fluid passage in response to upward and downward fluid flow therethrough, upper expander means carried by said mandrel for movement downwardly therewithin into sliding engagement with the upper portions of said slips to urge said upper portions into gripping engagement with the casing, lower expander means carried by said mandrel for movement upwardly therewith into sliding engagement with `the lower portions of said slips to urge said lower portions into gripping engagement with the casing, land releasable lock,- ing means for preventing premature setting engagement of said expander means and said slips.

9. In a bridge plug positionable within a casing, a tubular housing, friction means carried by said housing for engaging the casing, bridge plug slips having oppositely tapered upper and lower portions rigidly yconnected together at their wide ends and bearing casing gripping wickers on the ,outer arcuate faces thereof, pin and slot means pivotally and slidably mounting said 'slips on said housing for pivotal and radial movement outwardly into gripping engagement with the casing, a tubular mandrel received within said housing for limited longitudinal movement relative thereto, said tubular mandrel and housing defining a longitudinally extending fluid passage therethrough, oppositely directed packing cup assemblies carried by said mandrel for packing olf against said casing in response to pressure differentials acting upwardly and downwardly thereon, a first valve in said tubular mandrel movable to a closed position blocking said fluid passage in response to downward iluid iiow therethrough, a second valve in said tubular mandrel movable to a closed position blocking said fluid passage in response to upward uid flow therethrough, a retrieving head adapted` to be operatively connected-to a-tu`oing string for movein response to upward iiuidV flo-w therethrough, longitudinally spaced upper and lower expandermeans iixed to said mandrel for movement therewith, said mandrel moving downwardly in response to pressure differentials acting downwardly thereon when said rst valve is closed to slidably engage said upper expander means with said upper tapered portion of said slips and urge said upper portion wickers into gripping engagement with the casing,

said mandrel moving upwardly in response to pressure differentials acting upwardly thereon when said second valve is closed to slidably engage said lower expander means with said lower tapered portion of said slips to urge said lower portion wickers into gripping engagement with the casing, pin and slot means for guiding the longitudinal movement of said mandrel relative to said housing and for releasably limiting said longitudinal movement to prevent said expander means from moving into setting engagement with said slips, a retrieving head adapted to be operatively connected to a tubing string, and means releasably connecting said retrieving head and said upper valve and cooperating with said lower valve to move said valves to open positions allowing fluid flow through said mandrel in either direction.

11. In a packer positionable within a casing, a tubular housing, friction means carried by said housing for engaging the casing, a plurality of bridge plug slips arranged circumferentially about said housing, each of said slips including an upwardly tapered upper portion and a downwardly tapered lower portion rigidly connected together at their wide ends, said upper and lower portions each having an outer arcuate face provided with casing gripping serrations, means pivotally and slidably securing each of said slips to said housing intermediate said upper and lowerV portions, means for urging each of said slips to an inment therewith, a pin on said mandrel and a slot on said l retrieving head releasably connecting said retrieving head and mandrel, means operatively connecting said pin and said first valve and engageable with said second valve, said pin and connecting means being urged by said retrieving head to positions preventing said first and second valves from closing', whereby fluid by-passes said mandrel and housing, upper expander means carried by said mandrel for movement downwardly therewith into sliding engagement with the upper portion of said slips to urge said upper portion wickers into gripping engagement with the casing, lower expander means carried by said mandrel for movement upwardly into sliding engagement with the lower portion of said slips to urge said lower portion wickers into gripping engagement with the casing, and releasable locking means for preventing premature engagement of said expander means and slips.

l0. In a retrievable and resettable bridge plug positionable within a casing, a tubular housing, friction means carried by said housing for engaging the casing, bridge plug slips pivotally and slidably mounted on said housing for pivotal and radial movement outwardly into gripping engagement with the casing, Said slips each including an upwardly tapering upper portion having an outer arcuate face provided with casing gripping wickers and also iucluding a downwardly tapering lower portion rigidly connected to said upper portion and having an outer arcuate face provided wtih casing gripping wickers, means for urging said slips to -a retracted position, a tubular mandrel having a lower end slidably received within said housing for limited longitudinal movement therealong, said tubular mandrel and housing defining 'a longitudinally extending fluid passage therethrough, upwardly and downwardly directed packing cups mounted on said mandrel for packing off against the casing in response to pressure differentials 'acting upwardly and downwardly thereon, a first valve within said mandrel movable to a closed position blocking said fluid passage in response to downwardly fluid flow therethrough, a second valve movable to a closed position blocking said uid passage Wardly retracted position, a mandrel slidably received in said housing, upper expander means fixed to said mandrel and arranged to move downwardly therewith into wedging engagement with said upper portions of said slips to pivot said slips and slide said slips radially outwardly, whereby said upper portion serrations move into gripping engagement with the casing, lower expander means fixed to said mandrel and arranged to move upwardly therewith into wedging engagement with said lower portions of said slips to pivot said slips and slide said slips radially outwardly, whereby said lower portion serrations move into gripping engagement with the casing, locking means for releasably limiting the longitudinal movement of said mandrel relative to said housing to prevent said expander means from moving into wedging engagement with said slips, and means for moving said mandrel relative to haid housing.

12. In a packer positionable within a casing, a tubular housing, friction means carried by said housing for engaging the casing, a plurality of bridge plug slips arranged circumferentially about said housing, each of said slips including an upwardly tapered upper portion and a downwardly tapered lower portion rigidly connected together at their wide ends, said upper and lower portions each having an arcurate outer face provided with casing gripping serrations, pin and slot means pivotally and slidably securing each of said slips to said housing intermediate said upper and lower portions thereof, means for urging said slips to an inwardly retracted position, a tubular man drel slidably received within said housing, upper expander means fixed to said mandrel and arranged to move downwardly therewith into wedging engagement with said upper portions of said slips to pivot said slips and slide said slips radially outwardly, whereby said upper portion serrations move into gripping engagement with the casing, lower expander means fixed to said mandrel and arranged to move upwardly therewith into wedging engagement with'said lower portions of said slips to pivot said slips and slide said slips radially outwardly, whereby said lower portion serrations move into gripping engagement with the casing, pin and slot means on said mandrel and housing for guiding the longitudinal movement of said mandrel iii relative to said housing and for releasably limiting said longitudinal movement to prevent said expander means from moving into wedging engagement with said slips, and hydraulically actuated means for moving said mandrel longitudinally relative to said housing. ,Y

13. In a bridge plug positionable within a casing: a tubular housing, slip means carried by said housing for movement outwardly into gripping engagement with a casing, said slip means including unitary elongated slip members for engaging the casing, said members each having upper and lower inner surfaces inclined relative to one another to provide tapered ends on said slip members, a tubular mandrel having a lower end slidably received within said housing for limited longitudinal movement relative thereto, longitudinally spaced, oppositely inclined expander means carried by said mandrel for independently and alternately wedging said inner surfaces of said slip members to place said slip members into gripping engagement with the casing, elastomer packing means carried by said mandrel for packing olf against pressure differentials, valve means in said mandrel for blocking the llow of iiuid through said mandrel, and a retrieving head adapted to be releasably connected to said mandrel and to portions of said valve means to operate said valve means.

14. In a bridge plug positionable within a casing: a tubular housing, a tubular mandrel slidably received within said housing for limited longitudinal movement relative thereto, bridge plug slips carried by said housing for movement outwardly into gripping engagement with a casing, said slips having a unitary construction with upper and lower inner surfaces inclined relative to one another to provide tapered ends on said slips, means to resiliently bias said slips inwardly towards said tubular mandrel, a pair of longitudinally spaced expander means carried by said mandrel and on opposite sides of said slips for independently and alternately wedging said inner surfaces of said slips to place said slips into gripping engagement with the casing, packing means carried by said mandrel for packing ot against pressure differentials, valve means in said mandrel selectively operable to open and close the passageway through said mandrel, and a retrieving head adapted to be releasably connected to said mandrel to permit manipulation of said mandrel and said valve means.

l5. In a bridge plug positionable within a casing: a tubular housing, a'tubular mandrel slidably received within said housing for limited longitudinal movement relative thereto, bridge plug slips carried by said housing for movement outwardly into gripping engagement with a casing, said slips individually having outer serrated surfaces and inner tapered wedge surfaces, said wedge surfaces being oppositely inclined; means to resiliently bias said slips inwardly towards said tubular mandrel, a pair of longitudinally spaced expander means carried by said mandrel and on opposite sides of said slips, said expander means having inclined surfaces for independently and alternately wedging opposite ends of said slips into gripping engagement with the casing, packing means carried by said mandrel for packing oil against pressure differentials, valve means in said mandrel selectively operable to open and close the passageway through said mandrel, and a retrieving head adapted to be releasably cannected to said mandrel to permit manipulation of said mandrel and said valve means.

. References Cited in the file of this patent UNITED STATES PATENTS 2,607,424 Taylor Aug. 19, 1952 2,751,012 Baker et al 2...-..- June 19, 1956 2,799,346 Baker et al July 16, 1957 2,802,534 Conrad Aug. 13, 1957 

